Epstein-Barr virus (EBV) is a human herpes virus with a latent phase characterized by stable episomal propagation of a circular form of the viral DNA. Two discontinuous DNA elements are required for latent phase replication, the cis-acting origin of replication, OriP, and the Epstein-Barr Nuclear Antigen 1 (EBNA1), the sole virally encoded protein necessary for replication (Yates et al., Proc. Natl. Acad. Sci. USA 81:3806-10, 1984; Yates et al., Nature 313:812-5, 1985). Most EBV vectors are very large, on the order of 10 kb or more (without insert), because of the large size of the EBNA1 and OriP segments. The size of most existing EBV EBNA1 and OriP segments has interfered with the development of improved expression vectors and the creation of compact gene expression and persistence cassettes which can be embedded in other gene delivery vehicles, such as retroviruses or adenoviruses.